Tunable resistor with curved resistor elements

ABSTRACT

A resistor structure is provided that contains curved resistor elements. The resistor structure is embedded within an interconnect dielectric material and the resistivity of an electrical conducting resistive material of the resistor structure can be tuned to a desired resistivity during the manufacturing of the resistor structure. Notably, an electrical conducting metallic structure having a concave outermost surface is provided in a dielectric material layer. A doped metallic insulator layer is formed on the concave outermost surface of the metallic structure. A controlled surface treatment process is then performed to an upper portion of the doped metallic insulator layer to convert the upper portion of the doped metallic insulator layer into an electrical conducting resistive material. An interconnect dielectric material can then be formed to embed the entirety of the remaining doped metallic insulator layer and the electrical conducting resistive material.

BACKGROUND

The present application relates to a semiconductor structure and amethod of forming the same. More particularly, the present applicationrelates to a semiconductor structure that includes a tunable resistorstructure that contains curved resistor elements. The presentapplication also provides a method of forming such a semiconductorstructure.

A resistor, which is a passive two-terminal electrical component thatimplements electrical resistance as a circuit element, is one of themost common electrical components present in almost every electricaldevice. In electronic circuits, resistors can be used to limit currentflow, to adjust signal levels, bias active elements, and terminatetransition lines.

In semiconductor devices, it is well known to have a thin film resistorsuch as, for example, a resistor composed of TaN, embedded in the chipthrough either a damascene approach or a subtractive etch method. Forexample, and during back-end-of-the-line (BEOL) processing, a thin filmresistor may be embedded in an interconnect dielectric material. Priorart methods of forming thin film resistors embedded in an interconnectdielectric material are complicated and expensive. Moreover, topographyissues arise when embedding a thin film resistor in an interconnectdielectric material which may degrade the final chip yield. Other issueswith prior art methods of embedding a thin film metal resistor in a MOLdielectric material include variation of sheet resistivity and tuningprecision.

There is thus a need for providing a semiconductor structure including aresistor structure that is embedded in an interconnect dielectricmaterial that has design flexibility and controlled resistivity.

SUMMARY

The present application provides a resistor structure that containscurved resistor elements and is embedded within an interconnectdielectric material in which the resistivity of an electrical conductingresistive material of the resistor structure can be tuned to a desiredresistivity during the manufacturing of the resistor structure. Notably,an electrical conducting metallic structure having a concave outermostsurface is provided in a dielectric material layer. A doped metallicinsulator layer is formed on the concave outermost surface of themetallic structure. A controlled surface treatment process is thenperformed to an upper portion of the doped metallic insulator layer toconvert the upper portion of the doped metallic insulator layer into anelectrical conducting resistive material. An interconnect dielectricmaterial can then be formed to embed the entirety of the remaining dopedmetallic insulator layer and the electrical conducting resistivematerial.

In one aspect of the present application, a semiconductor structurecontaining a tunable resistor structure is provided. In one embodimentof the present application, the semiconductor structure includes anelectrical conducting metallic structure having a concave outermostsurface and embedded within a dielectric material layer. A curvedresistor structure is located on the concave outermost surface of theelectrical conducting metallic structure. The curved resistor structureincludes, from bottom to top, a doped metallic insulator and anelectrical conducting resistive material. An interconnect dielectricmaterial entirely embeds the curved resistor structure.

In another aspect of the present application, a method of forming asemiconductor structure is provided. In one embodiment, the method mayinclude providing an electrical conducting metallic structure having aconcave outermost surface and embedded in a dielectric material layer. Adoped metallic insulator layer is then formed on the concave outermostsurface of the electrical conducting metallic structure. Next, acontrolled surface treatment process is performed to an upper portion ofthe doped metallic insulator layer to convert the upper portion of thedoped metallic insulator layer into an electrical conducting resistivematerial, wherein a remaining portion of doped metallic insulator layerand the electrical conducting resistive material provide a curvedresistor structure. An interconnect dielectric material is then formedto embed the entirety of the curved resistor structure.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a cross sectional view of an exemplary semiconductor structureincluding a base substrate and a dielectric material layer that can beemployed in accordance with an embodiment of the present application.

FIG. 2 is a cross sectional view of the exemplary semiconductorstructure of FIG. 1 after forming an opening in the dielectric materiallayer.

FIG. 3 is a cross sectional view of the exemplary semiconductorstructure of FIG. 2 after forming a liner system including at least ametal liner within the opening and on a topmost surface of thedielectric material layer.

FIG. 4 is a cross sectional view of the exemplary semiconductorstructure of FIG. 3 after forming a layer of a metal or metal alloy onthe metal liner, wherein the metal or metal alloy of the layer of metalor metal alloy differs from the metal of the metal liner.

FIG. 5 is a cross sectional view of the exemplary semiconductorstructure of FIG. 4 after performing a planarization process in which anelectrical conducting metallic structure having a concave outermostsurface is provided.

FIG. 6 is a cross sectional view of the exemplary semiconductorstructure of FIG. 5 after forming a doped metallic insulator layer onthe concave outermost surface of the electrical conducting metallicstructure.

FIG. 7 is cross sectional view of the exemplary semiconductor structureof FIG. 6 after performing a controlled surface treatment in which anupper portion of the doped metallic insulator layer is converted into anelectrical conducting metallic nitride and/or oxide, wherein theremaining portion of the doped metallic insulator layer and theelectrical conducting metallic nitride and/or oxide provide a resistorstructure with curved resistor elements.

FIG. 8 is a cross sectional view of the exemplary semiconductorstructure of FIG. 7 after forming a dielectric capping layer onphysically exposed surfaces of the liner system, the resistor structure,and the dielectric material layer.

FIG. 9 is a cross sectional view of the exemplary semiconductorstructure of FIG. 10 after forming an interconnect dielectric materialon the dielectric capping layer.

FIG. 10 is a cross sectional view of the exemplary semiconductorstructure of FIG. 9 after forming a first contact structure thatcontacts a first portion of the resistor structure, and a second contactstructure that contacts a second portion of the resistor structure.

FIG. 11 is a top down view of the exemplary semiconductor structure ofFIG. 9 after forming an array of contact structures which can provide adifferent resistance to the resistor structure of the presentapplication.

DETAILED DESCRIPTION

The present application will now be described in greater detail byreferring to the following discussion and drawings that accompany thepresent application. It is noted that the drawings of the presentapplication are provided for illustrative purposes only and, as such,the drawings are not drawn to scale. It is also noted that like andcorresponding elements are referred to by like reference numerals.

In the following description, numerous specific details are set forth,such as particular structures, components, materials, dimensions,processing steps and techniques, in order to provide an understanding ofthe various embodiments of the present application. However, it will beappreciated by one of ordinary skill in the art that the variousembodiments of the present application may be practiced without thesespecific details. In other instances, well-known structures orprocessing steps have not been described in detail in order to avoidobscuring the present application.

It will be understood that when an element as a layer, region orsubstrate is referred to as being “on” or “over” another element, it canbe directly on the other element or intervening elements may also bepresent. In contrast, when an element is referred to as being “directlyon” or “directly over” another element, there are no interveningelements present. It will also be understood that when an element isreferred to as being “beneath” or “under” another element, it can bedirectly beneath or under the other element, or intervening elements maybe present. In contrast, when an element is referred to as being“directly beneath” or “directly under” another element, there are nointervening elements present.

Referring first to FIG. 1, there is illustrated an exemplarysemiconductor structure including a base substrate 10 and a dielectricmaterial layer 12 that can be employed in accordance with an embodimentof the present application. As is shown, the dielectric material layer12 is present on the entirety of the base substrate 10.

The base substrate 10 may be composed of a semiconductor material, aninsulator material, a conductive material or any combination thereof.When the base substrate 10 is composed of a semiconductor material, anymaterial having semiconducting properties such as, for example, Si,SiGe, SiGeC, SiC, Ge alloys, III/V compound semiconductors or II/VIcompound semiconductors, may be used. In addition to these listed typesof semiconductor materials, base substrate 10 can be a layeredsemiconductor such as, for example, Si/SiGe, Si/SiC,silicon-on-insulators (SOIs) or silicon germanium-on-insulators (SGOIs).

When the base substrate 10 is an insulator material, the insulatormaterial can be an organic dielectric material, an inorganic dielectricmaterial or any combination thereof including multilayers. The insulatormaterial that may provide the base substrate 10 is typically, but notnecessarily always, composed of a different dielectric material than thedielectric material layer 12. When base substrate 10 is a conductivematerial, base substrate 10 may include, for example, polySi, anelemental metal, alloys of elemental metals, a metal silicide, a metalnitride or any combination thereof including multilayers.

When base substrate 10 is composed of a semiconductor material, one ormore semiconductor devices such as, for example, complementary metaloxide semiconductor (CMOS) devices can be fabricated thereon. When basesubstrate 10 is composed of a combination of an insulator material and aconductive material, base substrate 10 may represent an underlyinginterconnect level of a multilayered interconnect structure.

The dielectric material layer 12 may include any interlevel orintralevel dielectric material including inorganic dielectrics ororganic dielectrics. A single interlevel or intralevel dielectricmaterial may be used, or a multilayered dielectric material stack of atleast two different interlevel or intralevel dielectrics may be used. Inone embodiment, the dielectric material layer 12 may be non-porous. Inanother embodiment, the dielectric material layer 12 may be porous. Someexamples of suitable dielectrics that can be used as the dielectricmaterial layer 12 include, but are not limited to, SiO₂,silsesquioxanes, C doped oxides (i.e., organosilicates) that includeatoms of Si, C, O and H, thermosetting polyarylene ethers, ormultilayers thereof. The term “polyarylene” is used in this applicationto denote aryl moieties or inertly substituted aryl moieties which arelinked together by bonds, fused rings, or inert linking groups such as,for example, oxygen, sulfur, sulfone, sulfoxide, carbonyl and the like.

The dielectric material that provides the dielectric material layer 12typically has a dielectric constant that is about 4.0 or less, with adielectric constant of about 2.8 or less being more typical. Alldielectric constants mentioned herein are relative to a vacuum, unlessotherwise noted. These dielectric materials generally have a lowerparasitic cross talk as compared with dielectric materials that have ahigher dielectric constant than 4.0. The thickness of dielectricmaterial that provides the dielectric material layer 12 may varydepending upon the type of dielectric material(s) used. In one example,the dielectric material that provides the dielectric material layer 12may have a thickness from 50 nm to 1000 nm. Other thicknesses that arelesser than, or greater than, the aforementioned thickness range mayalso be employed in the present application for the thickness of thedielectric material that provides the dielectric material layer 12.

The dielectric material that provides the dielectric material layer 12may be formed utilizing a deposition process such as, for example,chemical vapor deposition (CVD), plasma enhanced chemical vapordeposition (PECVD) or spin-on coating.

Referring now to FIG. 2, there is illustrated the exemplarysemiconductor structure of FIG. 1 after forming an opening 14 in thedielectric material layer 12. Although the present application describesand illustrates forming a single opening 14 into the dielectric materiallayer 12, a plurality of openings can be formed into the dielectricmaterial layer 12.

The opening 14 can be formed utilizing a patterning process. In oneembodiment, the patterning process may include lithography and etching.The lithographic process includes forming a photoresist (not shown) atopa material or material stack to be patterned, i.e., the dielectricmaterial layer 12, exposing the photoresist to a desired pattern ofradiation, and developing the exposed photoresist utilizing aconventional resist developer. The photoresist may be a positive-tonephotoresist, a negative-tone photoresist or a hybrid-tone photoresist.The etching process includes a dry etching process (such as, forexample, reactive ion etching, ion beam etching, plasma etching or laserablation), and/or a wet chemical etching process. Typically, reactiveion etching is used in providing the opening 14 into the dielectricmaterial layer 12. As is shown, the opening 14 stops within dielectricmaterial layer 12 exposing a sub-surface portion of the dielectricmaterial layer 12. By “sub-surface portion” it is meant a portion of amaterial that is located between a topmost surface and a bottommostsurface of the material.

The opening 14 may be a via opening, a line opening, and/or a combinedvia/line opening. In one embodiment, and when a combined via/lineopening is formed, a via opening can be formed first and then a lineopening is formed atop and in communication with the via opening. Inanother embodiment, and when a combined via/line opening is formed, aline opening can be formed first and then a via opening is formed atopand in communication with the line opening. In FIG. 2, and by way of anexample, the opening 14 is a via opening. When a combined via/line isformed a dual damascene process (including at least one iteration of theabove mentioned lithography and etching steps) can be employed.

Referring now to FIG. 3, there is illustrated the exemplarysemiconductor structure of FIG. 2 after forming a liner system 16including at least a metal liner 20 within the opening 14 and on atopmost surface of the dielectric material layer 12. The liner systemmay also include an optional diffusion barrier liner 18.

The metal that provides the metal liner 20 must be different from themetal or metal alloy that provides the subsequently formed layer ofmetal or metal alloy 22 (see, for example, FIG. 4). The metal for themetal liner 20 is chosen to provide a galvanic reaction to asubsequently formed layer of metal or metal alloy 22. The term “galvanicreaction” denotes the process by which two dissimilar metals (i.e., themetal liner and the subsequently formed layer of metal or metal alloy)that are in contact with each other begin to oxide or corrode. It isnoted that for a galvanic reaction to occur the following threeconditions need to meet. First, there must be two electrochemicaldissimilar metals present (in the present case the metal liner differsfrom the layer of metal or metal alloy to be subsequently formed).Second, there must be an electrically conductive path between the moreanodic metal to the more cathodic metal (in the present application andduring a subsequently performed planarization process there is anelectrically conductive path between the metal liner and the layer ofmetal or metal alloy to be subsequently formed). Third, there must be aconductive path for the metal ions to moved from the more anodic metalto the more cathodic metal (in the present application and during asubsequently performed planarization process there is a electricallyconductive path between the metal liner and the layer of metal or metalalloy to be subsequently formed).

In the present application, the metal liner 20 is chosen to provide apositive, i.e., faster, galvanic reaction to the subsequently formedlayer of metal or metal alloy 22. The metal liner 20 that provides thepositive galvanic reaction to the subsequently formed layer of metal ormetal alloy 22 will be employed to provide an electrical conductingmetallic structure having a concave outermost surface.

In the present application, the metal liner 20 is composed of a metalthat is more noble (slower oxidation rate) than the metal or metal alloyof the layer of metal or metal alloy 22 to be subsequently formed. Inone example, and when copper (Cu) is used as the layer of metal or metalalloy 22, ruthenium (Ru) can be used as the metal liner 20.

The metal liner 20 can be formed as a continuous layer utilizing adeposition process including, for example, chemical vapor deposition(CVD), plasma enhanced chemical vapor deposition (PECVD), atomic layerdeposition (ALD), physical vapor deposition (PVD), sputtering, chemicalsolution deposition or plating. The metal liner 20 may have a thicknessfrom 1 nm to 50 nm; although other thicknesses for the metal liner arecontemplated and can be employed in the present application so long asthe opening 14 is not entirely filled with the metal liner 20.

In some embodiments, the metal liner 20 is a sole component of the linersystem 16. In such an embodiment, the metal liner 20 directly contactsexposed surfaces of the dielectric material layer 12.

In yet other embodiments, a diffusion barrier liner 18 can be positionedbetween the metal liner 20 and the dielectric material layer 12. FIG. 3illustrates an embodiment in which the diffusion barrier liner 18 ispresent. When the diffusion barrier liner 18 is present, the diffusionbarrier liner 18 represents a lower liner material of the liner system16, while the metal liner 20 represents an upper liner material of theliner system 16.

When present, the diffusion barrier liner 18 is composed of a diffusionbarrier material. The diffusion barrier material that may provide thediffusion barrier liner 18 includes Ta, TaN, Ti, TiN, Ru, RuN, RuTa,RuTaN, W, WN, Co, CoN or any other material that can serve as a barrierto prevent a metal or metal alloy to be subsequently formed fromdiffusing there through. In some embodiments, the diffusion barriermaterial that may provide the diffusion barrier liner 18 may have athickness from 1 nm to 50 nm; although other thicknesses for thediffusion barrier material are contemplated and can be employed in thepresent application so long as the entirety of the opening 14 is notfilled with a diffusion barrier material.

The diffusion barrier material that may provide the diffusion barrierliner 18 can be formed by a deposition process including, for example,chemical vapor deposition (CVD), plasma enhanced chemical vapordeposition (PECVD), atomic layer deposition (ALD), physical vapordeposition (PVD), sputtering, chemical solution deposition or plating.

Referring now to FIG. 4, there is illustrated the exemplarysemiconductor structure of FIG. 3 after forming a layer of a metal ormetal alloy 22 on the metal liner 20, wherein the metal or metal alloyof the layer of metal or metal alloy 22 differs from the metal of themetal liner 20.

The metal or metal alloy that provides the layer of metal or metal alloy22 must be different from the metal used for the metal liner 20 suchthat a galvanic reaction is possible. Also, the metal or metal alloythat provides the layer of metal or metal alloy must provide a negative,i.e., slower, galvanic reaction as compared to the metal liner 20. Themetal or metal alloy that provides the layer of metal or metal alloy 22may include tantalum (Ta), tungsten (W), cobalt (Co), rhodium (Rh),ruthenium (Ru), aluminum (Al), copper (Cu), iridium (Jr), nickel (Ni) oralloys thereof. In one embodiment, the metal or metal alloy thatprovides the layer of metal or metal alloy 22 is composed of copper or acopper alloy.

The metal or metal alloy that provides the layer of metal or metal alloy22 can be formed utilizing a deposition process such as, for example,chemical vapor deposition (CVD), plasma enhanced chemical vapordeposition (PECVD), sputtering, chemical solution deposition or plating.In one embodiment, a bottom-up plating process is employed in formingthe metal or metal alloy that provides the layer of metal or metal alloy22.

As is shown in FIG. 4, the layer of metal or metal alloy 22 fills in theremaining volume of the opening 14 and includes an upper portion (alsoreferred to as an overburden portion) that extends outside the opening14 and above the topmost surface of the dielectric material layer 12.

Referring now FIG. 5, there is shown the exemplary semiconductorstructure of FIG. 4 after performing a planarization process in which anelectrical conducting metallic structure 24 having a concave outermostsurface 26 is provided. The term “concave” denotes a metal in which anupper portion thereof bulges inward.

The planarization process removes a portion of layer of metal or metalalloy 22, and a portion of the liner system 16, while leaving a portionof the layer of metal or metal alloy 22, and a portion of the linersystem 16 embedded within the opening 14. The planarization processcompletely removes the layer of metal or metal alloy 22 and the linersystem 16 from atop the dielectric material layer 12.

The electrical conducting metallic structure 24 constitutes a remainingportion of the layer of metal or metal alloy 22. The remaining portionof diffusion barrier liner 18 can be referred to herein as a U-shapeddiffusion barrier liner 18P, and the remaining portion of the metalliner 20 may be referred to herein as a U-shaped metal liner 20P. By“U-shaped” it is meant a material that contains a horizontal portion andtwo vertical portions that extend upward from opposing ends of thehorizontal portion. Thus, and after planarization, the liner system 16can now be referred to as a U-shaped liner system.

In some embodiments (not shown), a recess etch may be performed prior toplanarization to remove a portion of the overburden portion of the layerof metal or metal alloy 22. During the recess etch, no galvanic reactionoccurs.

In the present application, chemical mechanical polishing (CMP) is usedas the planarization process to provide the structure shown in FIG. 5;the term ‘chemical mechanical planarization’ can be used interchangeablywith the term ‘chemical mechanical polishing’. CMP is a process ofsmoothing surfaces with the combination of chemical and mechanicalforces.

Because the metal liner 20 is dissimilar to the layer of metal or metalalloy 22, a different removal rate occurs during the planarization whichfacilitates the formation of the electrical conducting metallicstructure 24 having the concave outermost surface 26. For example, andin the embodiment in which Ru is employed as the metal liner 20 and Cuis employed as the layer of metal or metal alloy 22, and since Ru ismore noble than Cu, the Ru removal rate during the planarization processis less than the removal rate of Cu, thus the electrical conductingmetallic structure 24 having the concave outermost surface 26 is formed.

Referring to FIG. 6, there is illustrated the exemplary semiconductorstructure of FIG. 5 after forming a doped metallic insulator layer 28 onthe concave outermost surface 26 of the electrical conducting metallicstructure 24. A portion of the doped metallic insulator layer 28 mayextend onto the U-shaped liner system (18P and/or 20P). In oneembodiment, the doped metallic insulator layer 28 is formed only uponthe electrical conducting metallic structure 24. In yet anotherembodiment, the doped metallic insulator layer 28 is formed upon theelectrical conducting metallic structure 24 and the U-shaped metal liner20P. In yet another embodiment, the doped metallic insulator layer 28 isformed on the electrical conducting metallic structure 24, the U-shapedmetal liner 20P and the U-shaped diffusion barrier liner 18P.

Doped metallic insulator layer 28 is a continuous (without any voidsand/or breaks) layer. In one embodiment, doped metallic insulator layer28 may include a nitrogen-doped metal that is composed of nitrogen, N,and a metal, M. In another embodiment, doped metallic insulator layer 28may include an oxygen-doped metal that is composed of oxygen, O, and ametal, M. In yet another embodiment, doped metallic insulator layer 28may include a nitrogen- and oxygen-doped metal that is composed ofnitrogen, N, oxygen, O, and a metal M. In any of the above mentionedembodiments, metal, M, is a ohmic material such as, for example,titanium (Ti), tantalum (Ta), ruthenium (Ru), tungsten (W), platinum(Pt), cobalt (Co), rhodium (Rh) and manganese (Mn). In one example, thedoped metallic insulator layer 28 is Ta₃N₅. In any of the abovementioned embodiments, the ratio of nitrogen and/or oxygen to metal inthe doped metallic insulator layer 28 provides a crystal structurehaving an insulating phase, which upon performing a subsequentcontrolled surface treatment is converted into an electrical conductingphase.

Doped metallic insulator layer 28 may be formed utilizing a selectivedeposition process such as, for example, chemical vapor deposition(CVD), plasma enhanced chemical vapor deposition (PECVD), atomic layerdeposition (ALD), and electroless plating.

Doped metallic insulator layer 28 may have a thickness of from 5 nm to50 nm. Other thicknesses that are lesser than 5 nm, or greater than 50nm can also be employed as the thickness of the doped metallic insulatorlayer 28.

Referring now to FIG. 7, there is illustrated the exemplarysemiconductor structure of FIG. 6 after performing a controlled surfacetreatment in which an upper portion of the doped metallic insulatorlayer 28 is converted into an electrical conducting metallic nitrideand/or oxide 30, wherein the remaining portion of the doped metallicinsulator layer (hereinafter the doped metallic insulator 28P) and theelectrical conducting metallic nitride and/or oxide 30 provide aresistor structure with curved resistor elements. Stated in anotherterms, the remaining portion of the doped metallic insulator layer(hereinafter the doped metallic insulator 28P) and the electricalconducting metallic nitride and/or oxide 30 provide a curved resistorstructure. The curved resistor structure follows the contour of theconcave outermost surface of the electrical conducting metallicstructure 24.

The term “metallic nitride and/or oxide” denotes a metallic nitride, ametallic oxide, or a metallic nitride-oxide. The electrical conductingmetallic nitride and/or oxide 30 includes the same metal as the dopedmetallic insulator layer 28. In one example, the electrical conductingmetallic nitride and/or oxide 30 is TaN. The electrical conductivemetallic nitride and/or oxide 30 may also be referred to herein as anelectrical conducting resistive material.

The controlled surface treatment process may include introducing atomsof nitrogen (N₂), atoms of oxygen (O₂), atoms of hydrogen (H₂), atoms ofargon (Ar) or any combination of the aforementioned atoms into the upperportion of the doped metallic insulator layer 28 such that theinsulating phase of the exposed portion of the doped metallic insulatorlayer 28 is converted into a crystal structure having an electricalconducting phase. In one embodiment, after the controlled surfacetreatment process, the ratio of oxygen and/or nitrogen in the upperportion of the doped metallic insulator layer 28 is changed such thatthe upper portion of the doped metallic insulator layer 28 is convertedfrom insulating to conducting. In one example, the doped metallicinsulator layer 28 (and thus the doped metallic insulator 28P) is Ta₃N₅,and the resulting electrical conducting resistive material (i.e., theelectrical conducting nitride and/or oxide 30) is TaN.

The controlled surface treatment process changes the composition of theexposed upper portion of the doped metallic insulator layer 28 into anelectrical conducting metallic material. Tuning of the resistivity ofthe resultant electrical conducting metallic material, i.e., theelectrical conducting metallic nitride and/or oxide 30, can be achievedby adjusting the depth of the controlled surface treatment process. Inone embodiment of the present application, the controlled surfacetreatment converts from 1 nm to 3 nm of the doped metallic insulatorlayer 28 into the electrical conducting resistive material. Other depthsare possible as long as at least a portion of the doped metallicinsulator layer 28 remains after the controlled surface treatmentprocess. As stated above, the remaining portion of the doped metallicinsulator layer 28 can be referred to as a doped metallic insulator 28P.

The controlled surface treatment may include, but is not limited to, athermal process, a plasma process, a gas cluster ion beam process, anion beam process or an ion implantation process.

The thermal process may include thermal treatments in an ambientcontaining at least one of nitrogen (N₂), oxygen (O₂), hydrogen (H₂),and argon (Ar). In one example, the thermal treatments may include athermal nitridation, and/or a thermal oxidation. The thermal processesdo not include an electrical bias higher than 200 W. The thermalprocesses may include a laser beam treatment. In some embodiments, noelectrical bias is performed during the thermal processes.

In one example, and when a thermal nitridation process is employed, thethermal nitridation process can be performed in any nitrogen-containingambient, which is not in the form of a plasma. The nitrogen-containingambients that can be employed in the present application include, butare not limited to, N₂, NH₃, NH₄, NO, or NH_(x) wherein x is between 0and 1. Mixtures of the aforementioned nitrogen-containing ambients canalso be employed in the present application. In some embodiments, thenitrogen-containing ambient is used neat, i.e., non-diluted. In otherembodiments, the nitrogen-containing ambient can be diluted with aninert gas such as, for example, helium (He), neon (Ne), argon (Ar) andmixtures thereof. In some embodiments, hydrogen (H₂) can be used todilute the nitrogen-containing ambient.

In another example, and when a thermal oxidation process is employed,the thermal oxidation process can be performed in any oxygen-containingambient, which is not in the form of a plasma. In one example, ozone(O₃) is employed as the oxygen-containing ambient. Other oxygencontaining ambients may also be employed. Mixtures of the aforementionedoxygen-containing ambients can also be employed in the presentapplication. In some embodiments, the oxygen-containing ambient is usedneat, i.e., non-diluted. In other embodiments, the oxygen-containingambient can be diluted with an inert gas such as, for example, helium(He), neon (Ne), argon (Ar) and mixtures thereof. In some embodiments,hydrogen (H₂) can be used to dilute the oxygen-containing ambient.

When a combined thermal nitridation and oxidation process is employed, acombination of nitrogen-containing and oxygen containing ambients usedneat or admixed with an inert gas or hydrogen can be employed.

In the specific examples mentioned above (i.e., thermal oxidation and/orthermal nitridation), the content of nitrogen (N₂) and/or oxygen (O₂)within the ambient employed in the present application is typically from10% to 100%, with a nitrogen and/or oxygen content within the ambientfrom 50% to 80% being more typical. In one embodiment, the thermalprocesses employed in the present application is performed at atemperature from 50° C. to 600° C.

Hydrogen (H₂) or argon (Ar) thermal processes can be performed neat ordiluted and the amounts of hydrogen (H₂) or argon (Ar) in such thermalprocesses can also be in the range from 10% to 100%.

When a plasma process is used, an electrical bias of greater than 200 Wcan be employed. The plasma process is performed by generating a plasmafrom one of the ambients (neat or diluted) that are mentioned above forthe thermal process; notably a plasma containing at least one ofnitrogen (N₂), oxygen (O₂), hydrogen (H₂), and argon (Ar) is providedand used during the controlled surface treatment process. In oneembodiment, the plasma process employed in the present application isperformed at a temperature from 50° C. to 600° C.

When an ion beam process is employed, a beam of at least one of nitrogen(N₂) ions, oxygen (O₂) ions, hydrogen (H₂) ions, and argon (Ar) ionsgenerated from an ion source such as one of the aforementioned ambientsis impinged upon the doped metallic insulator layer 28. The ion beamprocess may be performed utilizing any ion beam apparatus. The energy ofthe ion beam process can from 10 eV to 100 eV. The ion beam process canbe performed at a temperature from 50° C. to 600° C.

When a gas cluster ion beam process is employed, a cluster of at leastone of nitrogen (N₂) ions, oxygen (O₂) ions, hydrogen (H₂) ions, andargon (Ar) ions generated from an ion source such as one of theaforementioned ambients is impinged upon the doped metallic insulatorlayer 28. The gas cluster ion beam process may be performed utilizingany gas cluster ion beam apparatus. The energy of the gas cluster ionbeam process can from 10 eV to 30 eV. The gas cluster ion beam processcan be performed at a temperature from 50° C. to 600° C.

When ion implantation is employed, at least one of nitrogen (N₂) ions,oxygen (O₂) ions, hydrogen (H₂) ions, and argon (Ar) ions generated froman ion source such as one of the aforementioned ambients are impingedupon the doped metallic insulator layer 28. The ion implantation processmay be performed utilizing any ion implantation apparatus. The energy ofthe ion implantation process can from 10 eV to 200 eV. The ionimplantation process can be performed at a temperature from 50° C. to600° C.

Referring now to FIG. 8, there is illustrated the exemplarysemiconductor structure of FIG. 7 after forming a dielectric cappinglayer 32 on physically exposed surfaces of the U-shaped liner system(16P and/or 18P), the resistor structure (28P/30), and the dielectricmaterial layer 12. In some embodiments, the formation of the dielectriccapping layer 32 may be omitted.

When present, the dielectric capping layer 32 may include any dielectriccapping material such as, for example, silicon carbide (Si), siliconnitride (Si₃N₄), silicon dioxide (SiO₂), a carbon doped oxide, anitrogen and hydrogen doped silicon carbide (SiC(N,H)) or a multilayeredstack of at least one of the aforementioned dielectric cappingmaterials. The dielectric capping material that provides the dielectriccapping layer 32 may be formed utilizing a deposition process such as,for example, chemical vapor deposition (CVD), plasma enhanced chemicalvapor deposition (PECVD), atomic layer deposition (ALD), chemicalsolution deposition or evaporation.

When present, dielectric capping layer 32 may have a thickness from 10nm to 100 nm. Other thicknesses that are lesser than 10 nm, or greaterthan 100 nm may also be used as the thickness of the dielectric cappinglayer 32.

Referring now to FIG. 9, there is illustrated the exemplarysemiconductor structure of FIG. 10 after forming an interconnectdielectric material 34 on the dielectric capping layer 32. Inembodiments in which the dielectric capping layer 32 is omitted, theinterconnect dielectric material 34 may be formed on physically exposedsurfaces of the U-shaped liner system (16P and/or 18P), the resistorstructure (28P/30), and the dielectric material layer 12.

The interconnect dielectric material 34 may be composed of an inorganicdielectric material or an organic dielectric material. The interconnectdielectric material 34 comprises a different dielectric material thanthe dielectric capping layer 32. In some embodiments, the interconnectdielectric material 34 may be composed of a same dielectric material asthe dielectric material layer 12. In yet other embodiments, theinterconnect dielectric material 34 is composed of a differentdielectric material than the dielectric material layer 12.

In some embodiments, the interconnect dielectric material 34 may beporous. In other embodiments, the interconnect dielectric material 34may be non-porous. Examples of suitable dielectric materials that may beemployed as the interconnect dielectric material 34 include, but arelimited to, silicon dioxide, undoped or doped silicate glass,silsesquioxanes, C doped oxides (i.e., organosilicates) that includeatoms of Si, C, O and H, thermosetting polyarylene ethers or anymultilayered combination thereof.

The interconnect dielectric material 34 may have a dielectric constant(all dielectric constants mentioned herein are measured relative to avacuum, unless otherwise stated) that is about 4.0 or less. In oneembodiment, the interconnect dielectric material 34 has a dielectricconstant of 2.8 or less. These dielectrics generally having a lowerparasitic cross talk as compared to dielectric materials whosedielectric constant is greater than 4.0.

The interconnect dielectric material 34 may be formed by a depositionprocess such as, for example, chemical vapor deposition (CVD), plasmaenhanced chemical vapor deposition (PECVD) or spin-on coating. Theinterconnect dielectric material 34 may have a thickness from 50 nm to250 nm. Other thicknesses that are lesser than 50 nm, and greater than250 nm can also be employed as long as the interconnect dielectricmaterial 34 entirely embeds the resistor structure (28P/30) providedabove. That is, the interconnect dielectric material 34 must cover theentire resistor structure (28P/30).

Referring now to FIG. 10, there is illustrated the exemplarysemiconductor structure of FIG. 9 after forming a first contactstructure 36A that contacts a first portion of the resistor structure(28P/30), and a second contact structure 36B that contacts a secondportion of the resistor structure (28P/30). The first contact structure36A and the second contact structure 26B are spaced apart from eachother. The contact structures 36A, 36B make electrical contact with thedoped metallic insulator 28P and the electrically conductive resistiveelement 30 of the resistor structure.

Each contact structures (36A, 36B) can be formed by first providingcontact openings into the interconnect dielectric material 34 and, ifpresent, the dielectric capping layer 32. The contact openingsphysically expose different portions of resistor structure (28P/30).Each contact opening may be formed by lithography and etching as definedabove. After providing the contact openings, each contact opening isthen filled, at least in part, with a contact metal or metal alloy. Thecontact metal or metal alloy that provides at least a portion of thecontact structures (36A, 36B) may include tungsten (W), cobalt (Co),aluminum (Al), copper (Cu), or a copper-aluminum alloy (in such an alloycopper may compose a majority (i.e., greater than 50 atomic percent) ofthe alloy, aluminum may compose a majority (i.e., greater than 50 atomicpercent) of the alloy, or copper and aluminum are present in equalamounts (i.e., both elements are present at 50 atomic percent)).

The contact metal or metal alloy that provides at least a portion of thecontact structures (36A, 36B) can be formed by a deposition process suchas, for example, chemical vapor deposition (CVD), plasma enhancedchemical vapor deposition (PECVD), sputtering or plating. In someembodiments, a planarization process may follow the deposition of thecontact metal or metal alloy. In the illustrated embodiment, the contactstructures (36A, 36B) have a topmost surface that is coplanar with eachas well as being coplanar with a topmost surface of the interconnectdielectric material 34.

Referring now to FIG. 11, there is illustrated the exemplarysemiconductor structure of FIG. 9 after forming an array of contactstructures which can provide a different resistance to the resistorstructure of the present application. In this drawing, elements A, B, C,D, E and F represent contact structures that can be formed as describedabove. By varying the distance between the contact structures, it ispossible to provide different resistance to the resistor structure. Inthis illustrated embodiment, the resistance is as follows: AB<AC<AE<AF.

While the present application has been particularly shown and describedwith respect to preferred embodiments thereof, it will be understood bythose skilled in the art that the foregoing and other changes in formsand details may be made without departing from the spirit and scope ofthe present application. It is therefore intended that the presentapplication not be limited to the exact forms and details described andillustrated, but fall within the scope of the appended claims.

What is claimed is:
 1. A method of forming a semiconductor structure,the method comprising: providing an electrical conducting metallicstructure having a concave outermost surface and embedded in adielectric material layer; forming a doped metallic insulator layer onthe concave outermost surface of the electrical conducting metallicstructure; performing a controlled surface treatment process to an upperportion of the doped metallic insulator layer to convert the upperportion of the doped metallic insulator layer into an electricalconducting resistive material, wherein a remaining portion of dopedmetallic insulator layer and the electrical conducting resistivematerial provide a curved resistor structure; and forming aninterconnect dielectric material to embed the entirety of the curvedresistor structure.
 2. The method of claim 1, wherein the controlledsurface treatment process provides a phase change in the upper portionof the doped metallic insulator layer.
 3. The method of claim 2, whereinthe controlled surface treatment process comprises a thermal processperformed in an ambient including at least one of nitrogen, oxygenhydrogen and argon.
 4. The method of claim 2, wherein the controlledsurface treatment process comprises a plasma process performed in aplasma including at least one of nitrogen, oxygen hydrogen and argon. 5.The method of claim 2, wherein the controlled surface treatment processcomprises a gas cluster ion beam process performed in a gas clusterincluding at least one of nitrogen, oxygen hydrogen and argon
 6. Themethod of claim 2, wherein the controlled surface treatment processcomprises an ion beam process performed in a beam including at least oneof nitrogen, oxygen hydrogen and argon
 7. The method of claim 2, whereinthe controlled surface treatment process comprises an ion implantationprocess performed utilizing ions selected from at least one of nitrogenions, oxygen ions, hydrogen ions and argon ions.
 8. The method of claim1, wherein the electrical conductive resistive material is selected fromthe group consisting of a metallic nitride, a metallic oxide, and ametallic nitride-oxide.
 9. The method of claim 1, wherein the dopedmetallic insulator layer is selected from a nitrogen doped metal, anoxygen doped metal or a nitrogen and oxygen doped metal.
 10. The methodof claim 1, wherein the electrical conducting resistive material iscomposed of tantalum nitride (TaN) and the doped metallic insulatorlayer is composed of Ta₃N₅.
 11. The method of claim 1, wherein theproviding the electrical conducting metallic structure having theconcave outermost surface comprises: forming an opening in thedielectric material layer; forming a liner system including at least ametal liner in the opening and on an exposed surface of the dielectricmaterial layer; forming a layer of a metal or metal alloy on the metalliner, wherein the metal liner is composed of a metal that has apositive galvanic reaction to a metal or metal alloy that provides thelayer of metal or metal alloy; and performing a planarization process.12. The method of claim 11, wherein the forming the liner system furthercomprising forming a diffusion barrier liner located beneath the metalliner.
 13. The method of claim 11, wherein the metal liner is composedof ruthenium, and the layer of metal or metal alloy is composed ofcopper.
 14. The method of claim 11, wherein after performing theplanarization process, the liner system is converted into a U-shapedliner system comprising a U-shaped metal liner.
 15. The method of claim1, further comprising forming first and second contact structures in theinterconnect dielectric material.
 16. The method of claim 15, whereinthe first contact structure contacts a first end of the curved resistorstructure and the second contact structure contacts a second end of thecurved resistor structure.
 17. The method of claim 1, further comprisingforming an array of contact structures in the interconnect dielectricmaterial, wherein a distance between each contact structure is varied toprovide a different resistance to the curved resistor structure.